package com.hmdp.service.impl;

import cn.hutool.core.io.resource.ClassPathResource;
import com.hmdp.config.RedissonConfig;
import com.hmdp.dto.Result;
import com.hmdp.entity.SeckillVoucher;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIDWorker;
import com.hmdp.utils.SimpleRedisLock;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.Collections;
import java.util.concurrent.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Slf4j
@Service
@Transactional
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {
    @Resource
    private ISeckillVoucherService seckillVoucherService;
    @Resource
    private RedisIDWorker redisIDWorker;
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Autowired
    private RedissonConfig redissonConfig;
    @Autowired
    private RedissonClient redissonClient;
    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;
    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation((org.springframework.core.io.Resource) new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }

    private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024 * 1024);
    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();
    @PostConstruct
    private void init() {
        // 提交订单处理任务到线程池
        // VoucherOrderHandler 是一个持续运行的任务，会不断从阻塞队列中获取订单并处理
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }
    private class VoucherOrderHandler implements Runnable{
        @Override
        public void run() {
            while (true){

                try {
                    //1.获取阻塞队列中的订单信息
                    VoucherOrder voucherOrder = orderTasks.take();//获取队列中的头部，如果需要则等待,直到元素可用
                    //2.创建订单
                    handleVoucherOrder(voucherOrder);
                } catch (Exception e) {
                    log.info("处理订单异常",e);
                }
            }

        }
    }

        //  创建订单
        private void handleVoucherOrder(VoucherOrder voucherOrder) {

            // 1.获取用户
            Long userId = voucherOrder.getUserID();

            // 2. 创建分布式锁对象
            RLock lock = redissonClient.getLock("lock:order:" + userId);

            // 3.获取锁
            boolean isLock = lock.tryLock();

            // 4.判断获取锁是否成功
            if (!isLock){
                //获取锁失败,返回或重试
                log.info("不允许重复下单");
                return;
            }
            try {
                // 调用下单方法
                proxy.createVoucherOrder(voucherOrder);
            } finally {
                //释放锁
                lock.unlock();
            }
        }

        private IVoucherOrderService proxy;

        @Override
        public Result seckillVoucher(Long voucherId) {
            //获取用户
            Long userId  = UserHolder.getUser().getId();

            //1.执行Lua脚本
            Long result = stringRedisTemplate.execute(
                    SECKILL_SCRIPT,
                    Collections.emptyList(),
                    voucherId.toString(), userId.toString());

            //2.判断结果是否为0
            int r = result.intValue();
            if ( r != 0){
                //2.1 不为0 没有购买资格
                return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
            }

            // 2.2 为0 有购买资格,把下单信息保存到阻塞队列中
            // TODO 将用户id和优惠券id 保存到阻塞队列
            VoucherOrder voucherOrder = new VoucherOrder();
            long orderId = redisIDWorker.nextId("order:");
            // 2.3用户id
            voucherOrder.setUserId(userId);
            // 2.4订单id
            voucherOrder.setId(orderId);
            // 2.5代金券id
            voucherOrder.setVoucherId(voucherId);

            // 2.6 TODO 放入阻塞队列
            orderTasks.add(voucherOrder);

            // 3.获取代理对象
            proxy = (IVoucherOrderService) AopContext.currentProxy();

            // 4.返回订单id
            return Result.ok(orderId);
        }
    //分布式锁优化秒杀
//    @Override
//    public Result seckillVoucher(Long voucherId) {
//        //1.查询优惠券信息
//        SeckillVoucher voucher = seckillVoucherService.getById(voucherId);
//        //2.判断秒杀是否开始和结束
//        if(voucher.getBeginTime().isAfter(LocalDateTime.now())){
//            return Result.fail("秒杀尚未开始");
//        }
//        if(voucher.getEndTime().isBefore(LocalDateTime.now())) {
//            return Result.fail("秒杀已经结束");
//        }
//        //3.判断库存是否充足
//        if(voucher.getStock()<1){   //库存不足
//            return Result.fail("库存不足");
//        }
//        //4.扣减库存
//
//
//        //5.一人一单
//        //5.1查询订单
//        Long userId = UserHolder.getUser().getId();
//        // 创建锁对象
////        SimpleRedisLock lock = new SimpleRedisLock("order:" + userId, stringRedisTemplate);
//        RLock lock = redissonClient.getLock("lock:order:" + userId);
//
//        //获取锁
//        boolean isLock = lock.tryLock();
//        if (!isLock) {
//            //获取锁失败
//            return Result.fail("不允许重复下单");
//        }
//
//        try {
//            IVoucherOrderService proxy=(IVoucherOrderService) AopContext.currentProxy();
//            return proxy.getResult(voucherId);
//        } catch (IllegalStateException e) {
//            throw new RuntimeException(e);
//        } finally {
//            lock.unlock();
//        }
//
//
//    }
@Transactional
public Result getResult(Long voucherId) {
        Long userId = UserHolder.getUser().getId();

            //5.2 判断是否存在
            int count = query().eq("voucher_id", voucherId).eq("user_id", userId).count();
            if (count > 0) {
                return Result.fail("不能重复下单");
            }
            boolean success = seckillVoucherService
                    .update().setSql("stock = stock - 1")
                    .eq("voucher_id", voucherId).gt("stock",0)
                    .update();
            if (!success) {
                return Result.fail("库存不足");
            }
            //6.创建订单
            VoucherOrder voucherOrder = new VoucherOrder();
            //6.1.保存订单信息
            long orderId = redisIDWorker.nextId("order");
            voucherOrder.setId(orderId);
            //6.2.保存用户信息

            voucherOrder.setUserId(userId);
            //6.3.保存优惠券信息
            voucherOrder.setVoucherId(voucherId);
            save(voucherOrder);
            //7.返回订单id


            return Result.ok(orderId);

    }

    public void createVoucherOrder(VoucherOrder voucherOrder) {
        // 5. 一人一单
        Long userId = voucherOrder.getUserID() ;

        // 5.1 查询订单,查询当前用户是否已经购买过该优惠券

        int count = query().eq("user_id", userId)
                .eq("voucher_id", voucherOrder.getVoucherId()).count();

        // 5.2 一人一单 判断
        if (count>0){
            //用户已经购买过了
            log.info("用户已经购买过一次");
            return;
        }

        //6.乐观锁扣减库存,确保只有在库存大于0时才能进行扣减，防止超卖
        boolean success = seckillVoucherService.update()
                .setSql("stock = stock - 1") // set stock = stock -1
                .eq("voucher_id", voucherOrder.getVoucherId()).gt("stock",0)// where id =? and stock > 0?
                .update();
        if (!success){
            //扣减失败
            log.info("库存不足");
        }


        // 8.保存订单至数据库
        // 7.保存订单至数据库
        save(voucherOrder);

        //9.返回订单Id


    }
}
